Biomedical subjects

M Maisey

Publications and source records attributed to M Maisey.

At least 19 recordsLinked to original sources

PubMed2001

Early experience with PET scanning in thoracic tumours.

BACKGROUND: Positron emission tomography (PET) scan is an imaging technique which relies on metabolic properties of the lesions. In this study, we evaluated the potential contribution of PET for thoracic malignancy in a consecutive series of patients presenting with multiple lesions or equivocal diagnosis. METHODS: PET with 2-18 F fluorodeoxyglucose (FDG) was carried out in 41 patients. The diagnosis was primary intrathoracic malignancy in 22 (Group 1). On routine staging using CT scan we found 29 additional lesions and assessed these using PET scan. PET was performed to evaluate the number of metastatic lesions in the lung in 11 (Group 2), to characterise undiagnosed pathology in the chest in 4 (Group 3), to search clinically suspicious extrathoracic spread in 4 patients with known intrathoracic malignancy. RESULTS: In Group 1, the sensitivity and specificity of PET was 81.2% and 92.3%. The accuracy of PET in the confirmation of metastatic disease to the chest was 73%. PET was falsely positive in a patient with chronic inflammatory disease in Group 3 and highly accurate to characterise unknown pathology in Group 4. CONCLUSIONS: Even though infection may cause false positive results, PET is a useful imaging technique for the evaluation of patients with thoracic tumours.

Adult↗

PubMed2000

Positron emission tomography in imaging spinal cord tumors.

The ability of positron emission tomography (PET) to detect spinal cord tumors was studied prospectively in 14 patients presenting over a 5-year period. Abnormal uptake by [18F]-fluorodeoxyglucose (FDG) or 11C-methionine was detected in all except one. These data were assessed in relation to magnetic resonance imaging (MRI) findings with regard to tumor type and extent preoperatively, findings at operation, and subsequent clinical course. The group consisted of six astrocytomas, five ependymomas, one mixed ependymoma and astrocytoma, one schwannoma, and one ganglioglioma, all confirmed histologically. This is the largest study comparing spinal PET to MRI. Accurate preoperative correlation between PET and MRI was found in all eight patients scanned at first presentation. The PET uptake was in keeping with the low-grade histology of the tumors. Postoperatively, PET and MRI findings were in agreement in nine patients. In eight of these the findings were in keeping with the subsequent clinical course. In three patients, however, the PET findings were at variance with the clinical course and MRI findings. In one, persistent FDG uptake after radiotherapy was seen where there was subsequent tumor resolution. In two patients with low-grade astrocytomas, scanned with FDG and 11C-methionine, respectively, tracer was not taken up by residual tumor. In this small group of patients, PET did not provide additional useful information. This could be because all tumors studied were low grade and the limited spatial resolution of PET does not lend itself to imaging small spinal cord tumors. The prospective study of larger numbers of patients with a wider range of tumor types is required, but this might be difficult to achieve given the rarity of spinal cord tumors.

Adolescent↗

PubMed1999

Injection related anxiety in insulin-treated diabetes.

The presence of injection related anxiety and phobia may influence compliance, glycaemic control and quality of life in patients with insulin-treated diabetes. Unselected consecutive, insulin-treated patients attending a diabetes clinic for follow-up, completed a standardised questionnaire providing an injection anxiety score (IAS) and general anxiety score (GAS). A total of 115 insulin-treated (80 Type 1 and 35 Type 2) diabetic patients completed the questionnaire. Injections had been avoided secondary to anxiety in 14% of cases and 42% expressed concern at having to inject more frequently. An IAS > or = 3 was seen in 28% of patients and of these, 66% injected insulin one to two times/day, 45% had avoided injections, and 70% would be bothered by more frequent injections. A significant correlation between IAS and GAS was seen (Kendall's tau-a 0.30, 95% CI 0.19-0.41, P < 0.001). GAS was significantly associated with both previous injection avoidance and expressed concern at increased injection frequency. No significant correlation was seen with HbA1c and injection or general anxiety scores. Symptoms relating to insulin injection anxiety and phobia have a high prevalence in an unselected group of diabetic patients requiring insulin injections and are associated with higher levels of general anxiety.

Adult↗

PubMed1999

Use of positron emission tomography in evaluation of brachial plexopathy in breast cancer patients.

18-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has previously been used successfully to image primary and metastatic breast cancer. In this pilot study, 19 breast cancer patients with symptoms/signs referrable to the brachial plexus were evaluated with 18FDG-PET. In 11 cases computerized tomography (CT) scanning was also performed. Of the 19 patients referred for PET study, 14 had abnormal uptake of 18FDG in the region of the symptomatic plexus. Four patients had normal PET studies and one had increased FDG uptake in the chest wall that accounted for her axillary pain. CT scans were performed in 9 of the 14 patients who had positive brachial plexus PET studies; six of these were either normal or showed no clear evidence of recurrent disease, while three CTs demonstrated clear brachial plexus involvement. Of two of the four patients with normal PET studies, one has had complete resolution of symptoms untreated while the other was found to have cervical disc herniation on magnetic resonance imaging (MRI) scan. The remaining two patients almost certainly had radiation-induced plexopathy and had normal CT, MRI and PET study. These data suggest that 18FDG-PET scanning is a useful tool in evaluation of patients with suspected metastatic plexopathy, particularly if other imaging studies are normal. It may also be useful in distinguishing between radiation-induced and metastatic plexopathy.

Adult↗

PubMed1998

Selective use of PET scan in the preoperative staging of NSCLC.

Positron emission tomography (PET) is a imaging technique which identifies abnormalities by utilising their metabolic properties rather than their anatomical density. In this study, we evaluated the place of PET scanning for the characterisation of additional abnormalities discovered on routine, preoperative CT evaluation of patients with proven NSCLC. A total of 21 patients underwent PET scanning using fluorodeoxyglucose (FDG). In these patients, routine CT scans had found 26 concomitant lesions which were in lung, adrenal gland, liver, kidney, spleen and pleura. FDG uptake was positive at the primary site in all patients. FDG uptake in 13 of the concomitant lesions suggested malignancy. Malignancy was confirmed at all of these foci by histology in eight (six at thoracotomy, fine needle aspiration biopsy (FNAB) and open biopsy) and by clinical and radiological follow-up for 1-15 months in five. In 13 lesions, PET suggested benign disease. Histology reported no evidence of malignancy in five and the six foci followed on clinical and radiographic follow-up for 2-16 months had no evidence of malignancy. PET was falsely negative in only one site where malignancy was proven by thoracotomy. PET failed to detect the remaining lesion which was an unassociated primary kidney tumour in a patient with Li-Fraumeni syndrome. The accuracy of PET scanning in the assessment of those additional lesions found on CT evaluation of otherwise operable NSCLC was found to be 96% with a sensitivity of 93% and specificity of 100%. These results indicate that PET is useful to characterise additional lesions found on CT scan of patients with NSCLC.

Adult↗

PubMed1998

Regional differences in cerebral blood flow and glucose utilization in diabetic man: the effect of insulin.

To determine the effect of insulin on regional cerebral blood flow (rCBF) and glucose metabolism (CMRglu), we performed quantitative dynamic PET scanning of labeled water (H215O) and deoxyglucose (18FDG) using two protocols in 10 diabetic men. In protocol A, to test reproducibility of the technique, insulin was infused at 1.5 mU.kg-1.min-1 twice (n = 5). In protocol B, low (0.3 mU.kg-1.min-1) and high (3 mU.kg-1.min-1) dose insulin was given on separate occasions (n = 5). Euglycemia (5 mmol/L) was maintained by glucose infusion. In protocol A, CMRglu was 6% higher during the first infusion, and catecholamines were also increased, indicating stress. Blood flow was not different. Changing free insulin levels from 20.5 +/- 4.8 to 191 +/- 44.5 mU/L (P < 0.001, low versus high dose, protocol B) did not alter total or regional CMRglu (whole brain 36.6 +/- 4.0 versus 32.8 +/- 6.2 mumol.100 g-1.min-1, P = 0.32) or CBF (41.7 +/- 5.1 and 45.6 +/- 9.7 mL.100 g-1.min-1, P = 0.4) or rCBF. In cerebellum, CMRglu was lower than in cortex and the ratio between rate constants for glucose uptake and phosphorylation (K1 and k3) was reversed. There are regional differences in cerebral metabolic capacity that may explain why cerebral cortex is more sensitive to hypoglycemia than cerebellum. Brain glucose metabolism is not sensitive to insulin concentration within the physiologic range. This suggests that intracerebral insulin receptors have a different role from those in the periphery.

Adult↗

PubMed1998

Neuroimaging and spectroscopy in children with epileptic encephalopathies.

AIMS: To investigate the nature of the unifocal cortical abnormalities on FDG positron emission tomography (PET) in children with an epileptic encephalopathy but no focal abnormality on electroencephalogram or standard magnetic resonance imaging (MRI). METHODS: Repeat FDG PET, surface rendered high resolution MRI, and single voxel magnetic resonance proton spectroscopy of the areas of abnormal metabolism compared to the contralateral side in 11 children aged 2 to 12 years. Imaging was repeated after a median of 13 months. RESULTS: Visual analysis of repeat FDG PET revealed similar abnormalities in 10 of 11 children. Semiquantitative analysis revealed similar sited abnormalities in eight children. One child with ictal hypermetabolism initially had an inconsistent second scan. Magnetic resonance spectra in three children showed the N-acetyl-aspartate/choline ratio was lower in the hypometabolic focus than in the reciprocal area on the opposite side, in two children it was higher, and in one child it was equal. Surface rendered MRI was normal in seven of eight children, and showed temporal lobe asymmetry in one. CONCLUSION: In children with established epileptic encephalopathies most hypometabolic areas on FDG PET are stable over time. While focal neuronal loss is likely in these areas in some children, microdysplasias or other focal cortical dysplasias are probable in others.

Brain↗

PubMed1997

A prospective study of PET-FDG imaging for the assessment of head and neck squamous cell carcinoma.

The main aim of the study was to evaluate the use of positron emission tomography using fluoro-deoxyglucose (PET-FDG) imaging for the detection of squamous cell carcinoma of the head and neck. Fifty-four consecutive patients with malignancies involving the head and neck were studied prospectively. Thirty-one patients presented with primary disease and 23 were suspected of recurrent or residual disease. All patients underwent full clinical staging, PET-FDG scans and anatomical imaging, 37 underwent computed tomography (CT), 13 magnetic resonance (MR) and four had both CT and MR. Clinical assessment, CT/MR, PET-FDG and histological examination were all evaluated independently of each other. All 31 primary head and neck malignant tumours were detected by PET-FDG. Based on 16 patients who underwent neck dissections, the sensitivity and specificity of PET-FDG for detecting nodal disease was 67% and 100% respectively, compared with clinical assessment of 58% and 75% and CT/MR of 67% and 25%. In all 12 patients, PET-FDG correctly identified the presence of absence or recurrent or residual disease. PET-FDG staged 13 post-treatment necks with an accuracy of 100% as compared to CT/MR which was accurate in 7 of 13 and clinical assessment which was accurate in eight. Three sites of abnormal tracer uptake unrelated to malignancy were recorded as incidental findings (mandibular osteomyelitis, 1: post glossectomy site, 2). PET-FDG was more accurate than CT/MR for identifying primary and recurrent tumours as well as metastatic lesions in the neck. If these diagnostic properties of PET-FDG are confirmed in further prospective studies, it could prove a valuable adjunct for the management of head and neck cancer.

Aged↗

PubMed1997

On the usefulness of brain PET scanning to the paediatric neuro-oncologist.

Positron emission tomography (PET) scanning adds a functional dimension to brain scanning; levels of metabolic activity are imaged and this information may complement the more "anatomic" imaging of CT and MRI. In a series of 10 young patients the usefulness of PET scanning technique was investigated. The major areas of usefulness were the distinction of posttreatment sequelae from active tumour (both postsurgical MRI changes from tumour and postradiation MRI changes from tumour) and the localization of persisting tumour amenable to radiosurgical treatment. The technique was beneficial in assessing continuing activity in pineal tumours (residual pineal teratoma mass and residual pineocytoma mass) and in assessing activity in brainstem/cerebellar peduncle gliomas (three cases). In one unusual case of widespread leptomeningeal melanoma, the PET scan under-read the situation.

Adolescent↗

PubMed1997

Repetitive and non-repetitive violent offending behaviour in male patients in a maximum security mental hospital--clinical and neuroimaging findings.

OBJECTIVE: To examine if different violent offending behaviours are associated with different clinical and neuroimaging profiles. METHOD: Thirty-nine schizophrenic and schizoaffective offenders from a maximum security mental hospital-20 repetitive violent offenders (RVOs) and 19 non-repetitive violent offenders (NRVOs)-were selected for clinical and neuroimaging assessments. RESULTS: Both groups had positive family history of mental illness and violence. Age, diagnosis, duration of illness, victim profiles and use of weapons at the time of the index offence were similar. RVOs had a higher prevalence of early parental separation, juvenile conduct problem, previous convictions of crimes not involving violence, impulsive suicide attempts, delusion of their lives being threatened at the time of the index offence and electroencephalographic (EEG) abnormalities localized to temporal lobes. NRVOs had a higher prevalence of sexual inexperience and command hallucinations to kill at the time of the index offence. Asymmetric gyral patterns at the temporo-parietal region were particularly common in RVOs and absent in NRVOs. Non-specific white matter changes in magnetic resonance imaging (MRI) and generalized cortical hypometabolism in positron emission tomography (PET) were present in both groups. CONCLUSIONS: Different structural and metabolic changes in the brain were associated with different violent offending behaviours. The complex interaction between violent behaviour, clinical features and neuroimaging findings in schizophrenia requires further studies.

Adult↗

PubMed1996

Cardiac function, metabolism and perfusion in Duchenne and Becker muscular dystrophy.

We studied 23 DMD and eight BMD patients using cardiac echo, 24 h ECG and positron emission tomography (PET) with the radiotracers N-13 ammonia and F-18 fluorine deoxyglucose. The ECG was abnormal in 23 cases with alterations in the PR and/or QT intervals, abnormal Q waves in the lateral leads and ST segment depression. Twenty-four hour ECG showed that patients were more likely to produce premature ventricular ectopic beats with advancing age and 17 patients had paroxysmal ST segment depression. LV function was normal or mildly reduced in 24 cardiac echoes. PET studies were visibly abnormal in 15 patients. Regional perfusion defects involving the apex, lateral or anterior left ventricular walls were present, nine cases demonstrated a corresponding increase in glucose metabolism. Three out of 15 demonstrated matched perfusion/metabolism defects. One BMD had severe LV dilation with globally poor perfusion and metabolism. The abnormalities seen with PET were confirmed with both quantitative and semi-quantitative analysis of radioactive counts. Similar results were obtained for both DMD and BMD, where both groups demonstrated significant regional perfusion/metabolism mismatches. We have shown a reduced uptake of N-13 ammonia which is indicative of a reduction in myocardial perfusion. The use of N-13 ammonia to measure perfusion has been validated in animal studies. PET with either N-13 ammonia- or oxygen labelled water can be used to measure myocardial perfusion. We chose N-13 ammonia as this was most readily available to us.

Adolescent↗

PubMed1996

Validation and clinical application of computer-combined computed tomography and positron emission tomography with 2-[18F]fluoro-2-deoxy-D-glucose head and neck images.

BACKGROUND: Positron emission tomography with 2-[18F]fluoro-2-deoxy-D-glucose (PET-FDG) improves the detection of head and neck squamous cell cancer (HNSCC), but lacks anatomical detail. The accuracy of registered computed tomography/magnetic resonance (CT/MR) and PET-FDG in delineation of HNSCC at the primary site and its clinical application was investigated. METHOD: Preoperatively 30 patients were staged clinically and each had either CT (23), MR (5), or both CT and MR (2) scans, as well as CT/MR-PET-FDG registration. Tumor margins or infiltration of specific anatomical landmarks on the different scans were compared and judged against histology. RESULTS: For primary tumors CT-PET-FDG (97%) and MR-PET-FDG (100%) delineated the tumor more accurately than CT (69%) or MR (40%) alone. Similarly, CT-PET-FDG (98%) and MR-PET-FDG (100%) were better than CT (70%) and MR alone (80%) in identifying tumor invasion of specific anatomical structures. Management was altered in 7 of 30 patients. The registered images were particularly useful in delineating tumor extension in the infratemporal fossa, maxilla and mandible, and identifying recurrences obscured by scar tissue. CONCLUSIONS: It is possible to accurately register CT, MR, and PET-FDG data sets in the head and neck. The initial results show that registered CT/ MR-PET-FDG images provide additional clinically relevant information over that obtained from clinical evaluation or conventional CT/MR imaging.

Carcinoma, Squamous Cell↗

PubMed1996

The use of low-dose intravenous insulin in clinical myocardial F-18 FDG PET scanning.

The effectiveness of low-dose intravenous insulin boluses to improve study quality in F-18 FDG myocardial scans is investigated. Seventeen patients were imaged using a protocol in which only diabetic patients with fasting blood glucose levels > 8 mmol/l were given insulin. Fifty-three patients were imaged using a protocol in which all patients were given 1-3 IU intravenously of insulin immediately before F-18 FDG injection, based on fasting blood glucose levels. Scan quality was rated as poor, good, or excellent. Using the conventional protocol, 29% of the scans were poor quality (uniterpretable), 47% were good, and 23% were excellent. Using the low-dose intravenous insulin boluses protocol; 2% were poor, 53% were good, and 45% were excellent (P = 0.01). There were no significant differences in the proportion of diabetic patients, age, or fasting blood glucose levels. Low-dose intravenous insulin bolus is an easy and safe method of improving myocardial F-18 FDG scan quality in nondiabetic and diabetic patients.

Deoxyglucose↗

PubMed1996

Focal abnormalities detected by 18FDG PET in epileptic encephalopathies.

A prospective study of 32 children with epileptic encephalopathies 12 years or younger revealed a high incidence of focal cortical metabolic defects on 18-fluorodeoxyglucose positron emission tomography (PET) not suspected from clinical, EEG, or magnetic resonance imaging findings. PET scans were normal in all five children with typical de novo Lennox-Gastaut syndrome but showed cortical metabolic abnormalities in three out of four with atypical de novo Lennox-Gastaut syndrome, five out of six with Lennox-Gastaut syndrome following infantile spasms, six out of eight with severe myoclonic epilepsy in infancy, one out of two with epilepsy with myoclonic-astatic seizures, and four out of six with an unclassified epileptic encephalopathy. This suggests that some children with epileptic encephalopathies previously thought to have primary generalised seizures or seizures due to multifocal pathology may have unifocal cortical origin for their seizures. Such an origin may be amenable to surgery.

Child↗

PubMed1996

Evaluating the benefits of nuclear cardiology.

This paper reviews the role of nuclear cardiology in the context of health care evaluation and resource utilisation. Nuclear cardiology procedures are used to detect disease, to define the extent of disease, to predict the outcome of therapy and to monitor the response to treatment. The evaluation of the effectiveness will depend on the role for which the tests are being used. The evaluation of diagnostic tests most commonly follows the five level Fineberg classification. I) Technical capacity; II) diagnostic accuracy; III) diagnostic impact; IV) therapeutic impact; V) patient outcome. Tests may succeed or fail at each of these hierarchical levels. In addition to the clinical impact which is evaluated, the appropriate use of health care resources has to be considered, i.e. the cost effectiveness of the investigation. For this the costs of diagnosis and treatment in the resources used, together with the direct cost on the patient and patient carers needs to be considered. In addition to these direct costs to the community and to the patient and the carers the secondary downstream costs and opportunity costs have to be taken into account. The common methods for assessing the costs and benefits include cost minimalisation, cost effectiveness, cost utility, and cost benefit studies. The advantages and disadvantages and appropriate use of these methods are reviewed. There are seven clinical methods for evaluating diagnostic tests in nuclear cardiology which are: I) case reports; II) consensus studies; III) databases; IV) case control studies; V) modeling techniques; VI) management impact studies; VII) randomised control trial. Each of these has a role with advantages and disadvantages which are reviewed. It is no long sufficient to investigate the usefulness of a diagnostic test used in nuclear cardiology in isolation but it has to be within the context of the health care system and the resources used.

Coronary Disease↗

PubMed1991

Why clinical PET?

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Brain Diseases↗

PubMed1991

Clinical applications of positron emission tomography.

Positron emission tomography (PET) has been used extensively as a research tool in the investigation of human physiology and pathology for over a decade. By labelling suitable compounds (for example, glucose, amino acids, ammonia, DOPA or drugs) with positron emitting isotopes which are then administered in tracer amounts, the blood flow, metabolism and even the cell receptor or neurotransmitter distributions may be assessed in vivo. Advances in PET technology and experience now make PET a powerful clinical diagnostic tool, enabling investigation of disease at a molecular level, even in the absence of anatomical abnormalities apparent on computerised tomography (CT) or magnetic resonance imaging (MRI). Clinical PET is already utilised in the management of patients with epilepsy, cerebrovascular and cardiovascular disease, dementia and a wide variety of oncological applications. PET will become more widely available shortly in the UK, with the opening of centres such as the Guy's and St Thomas's Clinical PET Centre in 1992. It will therefore become increasingly important that clinicians are aware of those specific areas in which PET may be the investigation of choice to optimise patient diagnosis, treatment and/or follow-up. This review will endeavour to explain briefly the principles of the PET technique, and then outline those areas where PET has already had an impact on patient management in comparison with the more widely available diagnostic tests, finally outlining promising areas where PET may become more clinically useful in the future.

Coronary Disease↗

PubMed1989

Clinical and histological sequelae of Roux-en-Y diversion.

Nine post-Polya gastrectomy patients with symptoms of reflux gastritis were studied immediately before and 6 months after Roux-en-Y diversion with a 60 cm jejunal loop. Endoscopy, histology, HIDA radionuclide studies and acid secretory studies were performed to determine the effect of Roux-en-Y diversion. Symptomatic results were pleasing in that all patients were graded as Visick I or II. There was a statistically significant improvement in endoscopic evidence of mucosal damage (median score of 6 reduced to median of 1) and visible bile reflux (median score of 10.5 reduced to 0). Foveolar hyperplasia, superficial chronic gastritis and histological precursors of malignancy all improved. There was a significant decrease in the reflux of 99mTc-labelled HIDA into the gastric remnant while acid secretion remained unchanged. Roux-en-Y diversion with a 60 cm jejunal loop provides not only symptomatic relief but scintigraphic, endoscopic and histological evidence of pancreatobiliary diversion.

Aged↗